WEBVTT

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Hi everyone.

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In this video let me tell you the what is the controller in the.

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Nest.js.

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Now I will use the official documentation to show you the core concept.

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Now firstly, inside the overview and first step I will briefly about the previous video.

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So in the previous video we have a app controller.spec.ts and controller and app.module

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and app.service and main.ts.

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Right, now let's deeply understand about what's all of that

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Firstly.

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The app.controller.ts.

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This is the a basic controller with single route.

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Okay.

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And that's for the video.

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We will understand what is the controller in nestjs and with the controller.spec.ts, it will

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be the unit test for the controller.

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And we already remove that.

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Right.

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Because I don't want to write the test in this course.

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And the next thing will be the app.module.ts.

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This is the root module of application.

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We will understand what is the module and what is the root module in this course later.

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And the app service right here it will be the basic service with single methods.

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We will understand that later.

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Don't worry.

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and main.ts

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This is the entry file application.

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Okay.

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In nest factory, we can see nest factory right here to run the application.

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And now let's understand what's in the controller.

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I will click into the controller right here.

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The controllers are responsible for handle incoming requests and return response to the client.

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Right here, right now.

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Let's see what you mean when the client sends a request into the controller.

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Okay.

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For example, I have a client a client.

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I send a request.

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For example, I send a get method.

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Okay.

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Into the /product.

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I want to get the product of application.

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The NestJS, it will handle the traffic into something called controller okay.

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It will routing.

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It will route in the URL right here into the specific controller.

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So that's the idea of the controller.

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And in order to create the controller inside the Nest.js we use something called class and decorator.

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If you already are familiar with TypeScript you may know decorator right?

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Actually, you can see this is just the decorator with asterisk (at) and controller.

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In order to create controller, we use something like this.

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Controller.

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export and export class.

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Okay, make sure we export the class and we name it for the controller.

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And we define the some method like this.

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Okay.

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And for now I assume you are already familiar with get method or post.

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put patch and delete methods.

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And let me show you how we can create a controller.

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Now for example, right here I will create a new file called test.controller.ts and I will export

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class test controller.

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Okay.

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For example, right here we do the get method and we must import it from Nestjs/common.

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Okay.

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And right here I will specify the path to path right here.

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It can be undefined right.

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For example I will pass with products like this.

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And I will name it for method like find all products for example like this.

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And here I will return I will return the string.

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Maybe this a list of product.

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Now let's see.

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And the error right here it will come from prettierc & eslint

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I will fix that later.

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For now you can fix that using the right here.

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Okay.

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Inside the CRLF, we click on that and choose the LF option.

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Okay.

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I will fix that later.

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Don't worry about that.

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And I will go to the select product to see it.

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have or not localhost 3000 and /products right here.

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Right.

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If I go to now you can see it say the status will be four four.

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And the message cannot get product.

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And the error message will be not found.

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The reason it not found

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Because we have not yet setup

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Okay.

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We doesn't have set up successfully because we don't use the decorator controller right here, right.

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We can use the decorator called controller.

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And even that, if I refresh you can see it also 404

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Let's see what happened.

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The reason is 404 because we not apply that into the module.

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Then we apply that into the module.

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Don't worry, I will display the module in later.

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Firstly let's just import that into the controller right here.

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And if I refresh now you can see this is a list of products right.

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Very cool.

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And that's it.

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How to create a controller.

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Let me brief

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let me quickly show you.

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Firstly, we will use the decorator will be the controller.

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Right.

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And the second we must import it into the something called module.

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And with the module I will discuss.

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In maybe few next video.

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So that's the reason and how we can create a controller in Nest.js.

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I will see you in the next one.